cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A307290 Number of black-and-white colored (or proper magnetic) space groups in dimension n, counting enantiomorphs.

Original entry on oeis.org

0, 3, 46, 1191, 52439
Offset: 0

Views

Author

N. J. A. Sloane, Apr 08 2019

Keywords

Crossrefs

Formula

a(n) = A307291(n) - 2 * A006227(n). - Andrey Zabolotskiy, Apr 09 2019

Extensions

a(0), a(4) from Andrey Zabolotskiy, Apr 09 2019

A307293 Number of color plane groups of index n.

Original entry on oeis.org

17, 46, 23, 96, 14, 90, 15, 166, 40, 75, 13, 219, 16, 80, 34, 262, 14, 174, 15, 205, 38, 88, 13, 433, 31, 103, 48, 222, 14, 213, 15, 395, 36, 111, 24, 452, 16, 116, 40, 416, 14, 250, 15, 265, 62, 124, 13, 741, 32, 193, 38, 300, 14, 303, 24, 468, 42, 147, 13, 627, 16
Offset: 1

Views

Author

N. J. A. Sloane, Apr 08 2019

Keywords

Examples

			a(1) = A004029(2), a(2) = A307292(2).
		

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns, W. H. Freeman, New York, 1987, chapter 8 "Colored patterns and tilings".
  • Thomas W. Wieting, The Mathematical Theory of Chromatic Plane Ornaments, Marcel Dekker, Inc., 1982. See Table 11 at pages 250-254.

Crossrefs

Formula

a(p) = 16, 15, 14, 13 if p == 1, 7, 5, 11 (mod 12), respectively, and a(p^2) = a(p) + 17, where p is a prime greater than 3. These formulas are found by Senechal. Schwarzenberger (1983) says that her results are correct for these cases, while some other results have essentially been corrected by Wieting. - Andrey Zabolotskiy, May 18 2022

Extensions

a(1) and a(16)-a(60) from Wieting added by Andrey Zabolotskiy, Apr 09 2019
a(61) added by Andrey Zabolotskiy, May 18 2022
Showing 1-2 of 2 results.